1. Field of the Invention
The invention relates to boots adapted to be used for athletic practices in association with a gliding apparatus, for example, for sports on snow, or ice, skiing, or with a rolling apparatus, for example, in-line roller skates in which the boot portion is separable from the apparatus. The term gliding apparatus will hereinafter designate apparatuses that are strictly gliding as well as those equipped with wheels.
1. Description of the Background and Relevant Information
For the aforementioned types of sports, the boot is affixed to the apparatus during practice, with supports allowing the athlete to steer the apparatus, and retaining means to hold the feet on the apparatus.
When the athlete stops, he "removes the boot," i.e., he disengages the apparatus from the boots in order to be able to walk, and the object in these stopping phases is to have a boot allowing as normal a walk as possible.
However, and this is especially the case for alpine skiing, given that the bindings and the boots cooperate to ensure the skier's safety, the soles must have a set of geometric features and predefined qualities of friction. These requirements are specified for alpine skiing in the ISO 5355 standard.
Walking during the stopping phases cannot therefore occur in safety and comfort conditions worthy of the progress achieved elsewhere. With respect to walking comfort, one must consider a sole correctly designed for this function, i.e., having a shape allowing the movement of the foot and a material ensuring adherence and a certain shock absorption.
Additionally, since the ski boot is consistent with the standard requirements when it is put out on the market, the skier can think that his equipment will always be efficient and reliable. However, after a few hours of being used for walking, the quality of the sole/binding linkage can decrease substantially. The reasons are numerous: a wedge of snow under the boot when putting the ski on, dirt and incrustations in the sole, degradation in the normalized zones by wear due to walking, a poor adjustment induced, etc.
Finally, during athletic practice, the boot/binding assembly must ensure the transmission of forces from the skier to the ski. In the best current embodiments, the polygon formed by the boot/binding contact zones is of such a dimension that, associated with a sole worn and curved from walking, the assembly lends itself to a "hinge effect" due to the curving, all the more substantial since the binding adjustment is low.
The result is a decrease in the ski steering accuracy, which can cause the skier to increase the release values recommended for the binding adjustment in order to avoid ill-timed releases and to reconstitute the conditions of a good ski steering accuracy. Furthermore, to overcome this drawback, the boot manufacturer is led to raise and stiffen the boot upper, which translates into a lesser comfort and the rise of the traumatic risk towards the knee.
Current statistics confirm the phenomenon.
To answer this series of problems in part, the manufacturers have envisioned two lines of progress pertaining to the so-called safety binding.
The first consists in compensating for the degradation of the normalized surfaces of the boot by reducing the relative movement between the binding and the boot or with mechanisms creating punctual slackness of the abutment, avoiding "wedging" effects, therefore the increase in the release values. These solutions have little effect in the presence of an accentuated wear of the sole due to walking, and/or penalize the transmission of forces from the skier to the ski by installing an elasticity that "limits" these forces and by accentuating the previously mentioned "hinge effect." Another drawback is that this technique can cause ill-timed releases by offering a release value that is too low in certain fall configurations not indexed by the standard. The user is still tempted to increase his binding adjustments, which ruins the adjustment optimization effort by the manufacturer and puts himself in a dangerous position.
The second line consists in proposing so-called "plate" bindings. Two concepts emerged in this field, namely the plates affixed to the boot during the release and those remaining affixed to the ski under the same circumstances.
The first are described, for example, in the commonly owned patent FR 2 350 854, which discloses separating the "king" interface from the one cooperating with the binding; however, there are still drawbacks. Indeed, if one wishes to give a "walking" profile to the sole, the boot becomes "bastardized" and implies the simultaneous purchase of the boot, the plate and a "plate/ski" linkage system. This economic handicap has not enabled the development of this concept.
Another drawback is that the seating of the boot on the plate becomes unstable as soon as snow gets in between the plate and the sole of the boot, or as soon as the latter is worn and rounded off from walking, as mentioned previously. The problem with the ski steering accuracy due to the "hinge effect" described hereinabove therefore remains in its entirety.
Still another drawback is that in the case of a release on a steep icy slope, the plate remaining affixed to the boot becomes a handicap with respect to adherence and walking in recuperating his ski or skis.
The second ones were progressively called "boots/bindings." The plate portion, affixed to the ski and generally comprising the release system, cooperates with specific shapes integrated with the sole of the boot.
Such constructions are described in the FR 2 305 208, FR 2 533 448 and CH 507 007.
In the first patent FR 2 305 208, the wear of the sole and the accumulation of snow promoted by the walking profile leaves intact the problem of ski steering accuracy, due to the previously mentioned "hinge effect." Furthermore, the economical handicap remains in its entirety, the boot being able to cooperate only with the appropriate binding, and inversely. Finally, this type of mechanism has never been able to approximate, if not equal, the qualities of the abutment/heel concept.
In the second patent FR 2 533 448, the economical aspect is not questioned, the boot being capable of using the commercially available conventional bindings. The same goes for the instantaneous rotation center located plumb the tibia and fairly constant. Nevertheless, major handicaps have led to the abandonment of this concept, namely:
the blind fitting of the boot: the narrowness of the alpine ski and its mobility under the least impact makes the fitting almost impossible in many cases (rugged ground, slopes, etc.), PA1 the relationship between the plate and sole dimensions: indeed, if the dimension of the plate is sufficiently reduced to receive small sizes while preserving the normalized ends, it follows, especially in large sizes, a very disturbed longitudinal stability however little the sole is raised with respect to the ski. In this case, with the help of the binding elasticity, the release values will vary depending on the supports of the sole ends on the ski, these variables depending on the sizes and the presence or not of a wedge of snow, PA1 finally, the dimensions of the polygon formed by the previously described boot/plate contact zones are too reduced to ensure a correct transmission of the forces, in the transverse direction as much as in the longitudinal. PA1 it implies an extremely rigid sole given the distance of the supports (structure, cost, weight, etc.), PA1 the protuberances at the front and rear of the boot are exposed to impacts (the ends in particular are exposed), going up or down stairs, etc., PA1 since all of the forces are reflected directly to the binding (in particular, the abutment), it is understood that the functioning of the latter is disturbed by a variable weight (transfer of weight due to imbalances), PA1 fitting becomes extremely difficult, even impossible, if one wishes to take advantage of the raised position of the sole with respect to the ski, PA1 finally, the cost of an inseparable assembly is high.
As for the solution proposing several plate dimensions to cover all of the sizes, the cost is high, since the entire release mechanism, as well as the boot, are affected.
Finally, in various constructions of the "boots/bindings" type, at least a part of the walking surface of the sole is also the support surface on the ski or the binding. Here again, wear and deformations are incompatible with performance and safety. Commonly owned patent FR 2 654 591 shows this description.
In the third patent CH 507 007, a boot suspended at the front and rear ends on an abutment and a heel, respectively, is disclosed. This construction has been abandoned for several reasons:
Ski boots are also known whose shell comprises, at its lower portion, profiled notches adapted to the front and rear binding of the shell with respect to a rotative plate. These notches do not constitute support surfaces, but only retaining members replacing those existing in the ISO 5355 standard. The support remains the lower surface of the sole, therefore the "walking" surface.